Defect-free patterning of sol-gel-coated substrates for magnetic recording media

ABSTRACT

A method of manufacturing a magnetic recording medium comprises steps of providing a non-magnetic substrate for a magnetic recording medium, the substrate including at least one major surface; forming a layer of a sol-gel on the at least one major surface; forming a pattern, e.g., a servo pattern in an exposed surface of the layer of said sol-gel; and converting the layer of sol-gel to a glass or glass-like layer while preserving the pattern in an exposed surface of said glass or glass-like layer. Embodiments of the invention include magnetic media including a patterned glass or glass-like layer formed from a layer of a hydrophilic sol-gel with the pattern embossed therein by means of a stamper having a hydrophilic surface including a negative image of the pattern.

CROSS-REFERENCE TO PROVISIONAL APPLICATIONS

This application claims priority from U.S. provisional patentapplication Serial Nos. 60/221,219 and 60/221,460, each filed Jul. 25,2000, the entire disclosures of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for forming servopatterns in substrates for magnetic recording media utilized in highareal, high track density applications, and to magnetic recording mediaproduced thereby. The invention has particular utility in themanufacture of magnetic data/information storage and retrieval media,e.g., hard disks, utilizing very hard surfaced, high modulus substratessuch as of glass, ceramic, and glass-ceramic materials.

BACKGROUND OF THE INVENTION

Magnetic recording media are widely used in various applications,particularly in the computer industry. A portion of a conventionalrecording medium 1 utilized in disk form in computer-relatedapplications is schematically depicted in FIG. 1 and comprises anon-magnetic substrate 10, typically of metal, e.g., analuminum-magnesium (Al—Mg) alloy, having sequentially deposited thereona plating layer 11, such as of amorphous nickel-phosphorus (NiP), apolycrystalline underlayer 12, typically of chromium (Cr) or a Cr-basedalloy, a magnetic layer 13, e.g., of a cobalt (Co)-based alloy, aprotective overcoat layer 14, typically containing carbon (C), e.g.,diamond-like carbon (“DLC”), and a lubricant topcoat layer 15, typicallyof a perfluoropolyether compound applied by dipping, spraying, etc.

In operation of medium 1, the magnetic layer 13 can be locallymagnetized by a write transducer or write head, to record and storedata/information. The write transducer creates a highly concentratedmagnetic field which alternates direction based on the bits ofinformation being stored. When the local magnetic field produced by thewrite transducer is greater than the coercivity of the recording mediumlayer 13, then the grains of the polycrystalline medium at that locationare magnetized. The grains retain their magnetization after the magneticfield produced by the write transducer is removed. The direction of themagnetization matches the direction of the applied magnetic field. Thepattern of magnetization of the recording medium can subsequentlyproduce an electrical response in a read transducer, allowing the storedmedium to be read.

Thin film magnetic recording media are conventionally employed in diskform for use with disk drives for storing large amounts of data inmagnetizable form. Typically, one or more disks are rotated on a centralaxis in combination with data transducer heads. In operation, a typicalcontact start/stop (“CSS”) method commences when the head begins toslide against the surface of the disk as the disk begins to rotate. Uponreaching a predetermined high rotational speed, the head floats in airat a predetermined distance from the surface of the disk due to dynamicpressure effects caused by the air flow generated between the slidingsurface of the head and the disk. During reading and recordingoperations, the transducer head is maintained at a controlled distancefrom the recording surface, supported on a bearing of air as the diskrotates, such that the head can be freely moved in both thecircumferential and radial directions, allowing data to be recorded onand retrieved from the disk at a desired position. Upon terminatingoperation of the disk drive, the rotational speed of the disk decreasesand the head again begins to slide against the surface of the disk andeventually stops in contact with and pressing against the disk. Thus,the transducer head contacts the recording surface whenever the disk isstationary, accelerated from the static position, and duringdeceleration just prior to completely stopping. Each time the head anddisk assembly is driven, the sliding surface of the head repeats thecyclic sequence consisting of stopping, sliding against the surface ofthe disk, floating in air, sliding against the surface of the disk, andstopping.

It is considered desirable during reading and recording operations, andfor obtainment of high areal recording densities, to maintain thetransducer head(s) as close to the associated recording surface(s) as ispossible, i.e., to minimize the “flying height” of the head(s). Thus asmooth recording surface is preferred, as well as a smooth opposingsurface of the associated transducer head, thereby permitting the headand the disk surface to be positioned in close proximity, with anattendant increase in predictability and consistent behavior of the airbearing supporting the head during motion.

Disk drives typically comprise a magnetic head assembly mounted on theend of a support or actuator arm which positions the head radially overthe disk surface. If the actuator arm is held stationary, the magnetichead assembly will pass over a circular path on the disk surface knownas a track, and information can be read from or written to that track.Each concentric track has a unique radius, and reading and writinginformation from or to a specific track requires the magnetic head to belocated above the track. By moving the actuator arm, the magnetic headassembly is moved radially over the disk surface between tracks.

The disk drive must be able to differentiate between tracks on the diskand to center the magnetic head over any particular track. Most diskdrives use embedded “servo patterns” of magnetically recordedinformation on the disk. The servo patterns are read by the magnetichead assembly to inform the disk drive of the track location. Trackstypically include both data sectors and servo patterns. Each data sectorcontains a header followed by a data section. The header may includesynchronization information to synchronize various timers in the diskdrive to the speed of disk rotation, while the data section is used forrecording data. Typical servo patterns are described in, for example,U.S. Pat. No. 6,086,961, the disclosure of which is incorporated hereinby reference.

Servo patterns are usually written on the disk during manufacture of thedisk drive, after the drive is assembled and operational. The servopattern information, and particularly the track spacing and centeringinformation, needs to be located very precisely on the disk surface.However, at the time the servo patterns are written, there are noreference locations on the disk surface which can be perceived by thedisk drive. Accordingly, a highly specialized device known as a“servo-writer” is used during writing of the servo-patterns. Largelybecause of the locational precision needed, servo-writers are expensive,and servo-writing is a time-consuming process.

One approach (i.e., “PERM” disks, manufactured by Sony Corp.) to avoidtraditional servo-writing has been to injection mold or stamp servopatterns on a polymer-based substrate disk. A constant thickness layerof magnetic recording material is then applied over the entire disksurface, including the depressions and protrusions of the servopatterns. After all of the constituent layers of the medium have beenapplied to the disk, a magnetic bias is recorded on the servo patterns.For example, a first magnetic field may magnetically initialize theentire disk at a one setting. Then a second magnetic field, located atthe surface of the disk and e.g., provided by the magnetic head of thedisk drive, is used to magnetize the protruding portions of the servopatterns relative to the depressions. Because the protrusions are closerthan the depressions to the magnetic initialization, the magnetizationcarried by the protrusions may be different than the magnetizationcarried by the depressions. When read, the resulting disk servo patternsshow magnetic transitions between the depressions and the protrusions.

Meanwhile, the continuing trend toward manufacture of very high arealdensity magnetic recording media at reduced cost provides impetus forthe development of lower cost materials, e.g., polymers, glass,ceramics, and glass-ceramics composites as replacements for theconventional Al alloy-based substrates for magnetic disk media. However,poor mechanical and tribological performance, track mis-registration(“TMR”), and poor flyability have been particularly problematic in thecase of polymer-based substrates fabricated as to essentially copy ormimic conventional hard disk design features and criteria. On the otherhand, glass, ceramic, or glass-ceramic materials are attractivecandidates for use as substrates for very high areal density diskrecording media because of the requirements for high performance of theanisotropic thin film media and high modulus of the substrate. However,the extreme difficulties encountered with grinding and lapping of glass,ceramic, and glass-ceramic composite materials have limited their use toonly higher cost applications such as mobile disk drives for“notebook”-type computers.

Presently, media anisotropy is achieved by circumferentially polishing(“mechanically texturing”) Al alloy substrates with NiP plating layersusing a diamond or other relatively hard abrasive in slurry formdispensed on an absorbent and compliant polishing pad or tape.Sub-micron flyability (e.g., <0.5 μinch) of the recording transducer orhead over a is a requirement for obtainment of very high areal densityrecording media. However, attempts to achieve the requisite surfacetopography on glass, ceramic, or glass-ceramic composite substrates havebeen unsuccessful due to their extreme hardness (e.g., glass substrateshave a Knoop hardness greater than about 760 kg/mm² compared with about550 kg/mm² for Al alloy substrates with NiP plating layers). Inaddition, the low flowability and extreme hardness of these substratematerials effectively precludes formation of servo patterns in thesurfaces thereof by injection molding or stamping, as has been performedwith polymer-based substrates.

In view of the above, there exists a need for improved methodology andmeans for providing disk substrates for magnetic recording media, whichsubstrates are constituted of very hard materials, with at least onesurface of requisite topography for enabling operation with flying headread/write transducers/heads operating at very low flying heights andwith servo patterns provided therein, as by embossing. Morespecifically, there exists a need for an improved means and methodologyfor embossing a pattern, i.e., a servo pattern, in a surface of asubstrate for a magnetic recording medium, comprised of a glass,ceramic, or glass-ceramic composite material. In addition, there existsa need for an improved, high areal density magnetic recording mediumincluding a high hardness, high modulus substrate having a servo patternintegrally formed therewith, as by embossing.

The present invention addresses and solves problems and difficultiesattendant upon the use of very hard materials, e.g., of glass, ceramic,or glass-ceramic, as substrate materials in the manufacture of very highareal density magnetic recording media, while maintaining fullcapability with substantially all aspects of conventional automatedmanufacturing technology for the fabrication of thin-film magneticmedia. Further, the methodology and means afforded by the presentinvention enjoy diverse utility in the manufacture of various otherdevices and media requiring formation of patterned surfaces by embossingof high hardness materials.

DISCLOSURE OF THE INVENTION

An advantage of the present invention is an improved method ofmanufacturing a magnetic recording medium including a patterned surface.

Another advantage of the present invention is an improved method ofmanufacturing a magnetic recording medium including a high modulussubstrate having a servo-patterned glass or glass-like layer formed on asurface thereof.

Yet another advantage of the present invention is an improved magneticrecording medium including an embossed servo pattern formed therein andcapable of operation with transducer heads at sub-micron flying heights.

Still another advantage of the present invention is an improved magneticrecording medium comprised of a high modulus substrate including asintered glass or glass-like layer formed thereon and having a servopattern formed therein.

A further advantage of the present invention is a stamper having ahydrophobic surface for embossing a servo pattern in the surface of ahydrophilic sol-gel layer formed on a surface of a high modulussubstrate for a magnetic recording medium.

Additional advantages and other aspects and features of the presentinvention will be set forth in the description which follows and in partwill become apparent to those having ordinary skill in the art uponexamination of the following or may be learned from the practice of thepresent invention. The advantages of the present invention may berealized and obtained as particularly pointed out in the appendedclaims.

According to an aspect of the present invention, the foregoing and otheradvantages are obtained in part by a method of manufacturing a magneticrecording medium, comprising the sequential steps of:

(a) providing a non-magnetic substrate for a magnetic recording medium,the substrate including at least one major surface;

(b) forming a layer of a sol-gel on the at least one major surface ofthe substrate;

(c) forming a pattern in an exposed surface of the layer of the sol-gel;and

(d) converting the layer of the sol-gel to a glass or glass-like layerwhile preserving the pattern in an exposed surface of the glass layer.

According to embodiments of the present invention, step (a) comprisesproviding a disk-shaped, high modulus substrate having a pair of majorsurfaces and comprised of a glass, ceramic, or glass-ceramic material;step (b) comprises forming the layer of the sol-gel by spin coating asolution of the sol-gel on the at least one major surface of thesubstrate; and step (c) comprises embossing a servo pattern in theexposed surface of the layer of the sol-gel by applying thereto asurface of a stamper, the surface of the stamper including a negativeimage pattern of the servo pattern.

In accordance with embodiments of the present invention, step (b)comprises forming a layer of a hydrophilic sol-gel on the at least onemajor surface of the substrate; and step (c) comprises embossingutilizing a stamper wherein at least the patterned surface thereof isformed of a hydrophobic material.

According to particular embodiments of the invention, step (c) comprisesutilizing a stamper wherein at least the patterned surface thereof isformed of a hydrophobic polymeric material; e.g., an amorphousthermoplastic material selected from polycarbonates, polyetherimides,polypropylenes, and polyethylenes; or step (c) comprises utilizing astamper having a main body comprised of a first metal and the patternedsurface thereof is formed of a second metal, carbon (C), or ahydrophobic polymer e.g., the main body is comprised of nickel (Ni) andthe patterned surface thereof is formed of platinum (Pt), carbon (C), ora sputtered hydrophobic polymer.

In accordance with embodiments of the present invention, step (d)comprises sintering the layer of sol-gel at an elevated temperature; andstep (b) comprises forming a layer of a sol-gel comprising a porouslayer of SiO₂ containing water and at least one solvent in the poresthereof, wherein step (d) comprises converting the layer of sol-gel tothe glass or glass-like layer by driving out the water and the at leastone solvent from the pores by sintering the layer of sol-gel at atemperature of from about 300 to above about 1000° C.

According to embodiments of the present invention, the method furthercomprises the step of:

(e) forming a stack of thin film layers over the exposed surface of theglass or glass-like layer, the stack of layers including at least oneferromagnetic layer.

Another aspect of the present invention is a magnetic recording medium,comprising:

(a) a non-magnetic substrate having at least one major surface;

(b) a sintered glass or glass-like layer formed on the at least onemajor surface, the sintered glass or glass-like layer including an uppersurface having an embossed pattern formed therein; and

(c) a stack of thin film layers formed over the upper surface of thesintered glass or glass-like layer, the stack of layers including atleast one ferromagnetic layer.

In accordance with embodiments of the present invention, thenon-magnetic substrate (a) is disk-shaped with a pair of major surfacesand comprised of a high modulus material selected from glass, ceramic,and glass-ceramic materials; and the sintered glass or glass-like layer(b) is derived from a sol-gel layer and includes an embossed servopattern formed therein.

Yet another aspect of the present invention is a stamper for embossing aservo pattern in a surface of a layer of a hydrophilic sol-gel formed ona surface of a substrate for a magnetic recording medium, comprising:

(a) a main body having an embossing surface including a negative imageof the servo pattern; and

(b) means for facilitating release of the embossing surface of thestamper from the surface of the layer of sol-gel subsequent to embossingof the servo pattern.

According to particular embodiments of the present invention, the mainbody and the embossing surface of the stamper are formed of ahydrophobic polymeric material, e.g., an amorphous thermoplasticmaterial selected from polycarbonates, polyetherimides, polypropylenes,and polyethylenes; whereas, according to other particular embodiments ofthe present invention, the main body is formed of a first metal and theembossing surface is formed of a second metal, carbon, or a hydrophobicpolymer, e.g., the first metal is nickel and the embossing surface ismade of platinum, carbon, or a sputtered hydrophobic polymer.

Additional advantages and aspects of the present invention will becomereadily apparent to those skilled in the art from the following detaileddescription, wherein embodiments of the present invention are shown anddescribed, simply by way of illustration of the best mode contemplatedfor practicing the present invention. As will be described, the presentinvention is capable of other and different embodiments, and its severaldetails are susceptible of modification in various obvious respects.Accordingly, the drawings and description are to be regarded asillustrative in nature, and not as limitative.

BRIEF DESCRIPTION OF THE DRAWING

The following detailed description of the embodiments of the presentinvention can best be understood when read in conjunction with thefollowing drawing, in which the features are not necessarily drawn toscale but rather are drawn as to best illustrate the pertinent features,wherein:

The FIGURE illustrates, in schematic, simplified cross-sectional view, aportion of a thin film magnetic data/information recording/storagemedium.

DESCRIPTION OF THE INVENTION

The present invention addresses and solves problems attendant upon theuse of very hard surfaced, high modulus materials, e.g., of glass,ceramics, or glass-ceramic composites, as substrates in the manufactureof thin film, high areal density magnetic recording media, and is basedupon the discovery that the surfaces of such materials may be modified,i.e., reduced in hardness, so as to facilitate formation of servopatterns therein, as by a simple and conveniently performed embossingprocess. According to the invention, modification (i.e., reduction) ofsurface hardness of high modulus substrates for use in the manufactureof thin film magnetic recording media is obtained by first forming arelatively soft coating layer on the substrate surface, embossing thedesired servo pattern in the exposed upper surface of the relativelysoft coating layer, and then converting the relatively soft layer to arelatively hard layer while retaining the embossed servo patterntherein. The thus-formed substrate with embossed servo pattern in theexposed surface thereof is then subjected to thin film depositionthereon for forming the layer stack constituting the magnetic recordingmedium. The inventive methodology advantageously providesservo-patterned magnetic recording media without requiring servo-writingsubsequent to media fabrication.

More specifically, according to the present invention, a relatively softlayer of a sol-gel is initially formed on the surface of the highmodulus glass, ceramic, or glass-ceramic composite substrate, e.g., indisk form. By way of illustration, but not limitation, a sol-gel layerhaving a thickness of from about 0.2 to about 1 μm may be formed on thesubstrate surface by any convenient technique, e.g., spin coating of asolution of the sol-gel. A suitable sol-gel solution for use accordingto the invention may be prepared by mixing an alkoxide, e.g., a siliconalkoxide such as tetraethoxysilane (“TEOS”) or tetramethoxysilane(“TMOS”), water, and nitric acid at molar ratios of TEOS orTMOS/H₂O/HNO₃ of 1/4-30/>0.05. The nitric acid acts as a catalyst forconversion of the TEOS or TMOS to a SiO₂ sol according to the followingreaction, illustratively shown for TEOS:

nSi(OC₂H₅)₄+2nH₂O→nSiO₂+4nC₂H₅OH

with ethanol (C₂H₅OH) being produced as a reaction product in solution.After completion of reaction, butanol (C₄H₉OH) is added to the solutionas a drying retardation agent at molar ratios of TEOS/H₂O/HNO₃/C₄H₉OH ofe.g., 1/5/0.05/>4. Such solution, when applied to the substrate surfaceas by spin coating, forms a very smooth film with a minimum amount ofsurface microwaves. The resultant film or layer is glass-like,principally comprised of silica (SiO₂) molecular clusters together withthe various solvents (H₂O, C₂H₅OH, C₄H₉OH), and adheres well to thesubstrate surface. The sol-gel film or layer is of a porous structurewith the solvents saturated in the micropores thereof.

According to the inventive methodology, the as-deposited, relativelysoft sol-gel film or layer applied to the hard-surfaced substrate isthen subjected to an embossing process for forming a servo pattern inthe surface thereof, comprising a patterned plurality of depressions andprotrusions, e.g., by utilizing a stamper having a negative image of thedesired servo pattern or an equivalently performing device. The exposed,upper surface of the relatively soft sol-gel layer may also be subjectedto mechanical texturing (after drying in air but prior to sintering),e.g., as by a standard NiP texturing process utilizing an abrasive sizeof about 0.25 μm, in order to enable formation of oriented mediacritical for achieving high areal density recording.

Subsequent to servo pattern formation (and mechanical texturing, ifdesired) of the as-deposited, relatively soft sol-gel film or layer, asintering process is performed at an elevated temperature of from about300 to above about 1000° C. (depending upon the withstand temperature ofthe substrate material, i.e., which temperature is higher forceramic-based substrates than for glass-based substrates) at e.g., aramping rate from about 0.5 to about 10 ° C./min. and a dwell time ofabout 2 hrs., to evaporate the solvents so as to effect at least partialcollapse of the micro-pores, with resultant densification of the sol-gelfilm or layer into a substantially fully densified glass layer having adensity and hardness approaching that of typical silica glass (<1.5g/cm³), or into a partially densified “glass-like” layer. The embossedservo pattern (and mechanical texturing) formed in the exposed uppersurface of the relatively soft sol-gel layer is preserved in thecorresponding exposed upper surface of the sintered glass or glass-likelayer. Formation of thin film magnetic media on the thus-formedglass-coated, servo patterned/mechanically textured substrates isaccomplished utilizing conventional thin film deposition techniques,e.g., sputtering, for forming the layer stack comprising apolycrystalline underlayer, magnetic layer, and protective overcoatlayer.

As indicated above, according to the invention, the step of forming theservo pattern in the exposed, upper surface of the relatively softsol-gel film or layer by embossing is typically performed with a stamper(or equivalently performing device) having a negative image of thedesired servo pattern. Clean release of the stamper from the sol-gelfilm or layer without sticking is critical for obtaining defect-freeservo-patterned surfaces. However, experimentation by the inventorsdetermined that stampers fabricated of nickel (Ni) such as are employedin the manufacture of compact discs (CDs) for plastic molding/patternformation, tend to adhere to the surface of the sol-gel film or layer,resulting in surface defects arising from the pulling away or severingof portions of the sol-gel layer from the underlying substrate surface.The inventors have determined that, for satisfactory, or “clean” releaseof the stamper from the sol-gel layer surface to occur, the patternedsurface of the stamper must be sufficiently different from that of thesol-gel. In particular, the inventors determined that the sol-gel has ahydrophilic surface, and therefore the stamper must have a hydrophobicsurface in order to facilitate clean release or separation.

According to a first approach developed by the inventors, the stamperwas fabricated from polymeric materials, via injection molding utilizinga Ni “mother” stamper having a servo pattern comprised of a plurality ofpits to form a polymeric “child” stamper having a servo patterncomprised of a corresponding plurality of protrusions. However, the highviscosity of the polymer melt imposed a great challenge in filling thesub-micron dimensioned pits to produce correspondingly dimensionedprotrusions on the polymeric stamper with a high degree of reproductionfidelity. Polymer-based stampers with high reproduction fidelityprotrusions suitable for use in the servo-patterning process of theinvention were successfully obtained by utilizing a very high moldtemperature, i.e., close to the T_(g) of the polymeric material, whereT_(g) is the critical temperature separating glassy behavior of thepolymeric material from rubbery behavior, with T_(g) typically beingfrom about 85 to about 285 ° C. for most engineering plastics, e.g.,about 150 ° C for polycarbonate and about 217 ° C. for polyetherimide,very high injection rates (e.g., from about 170 to about 190 cm³/sec.),and high melt temperature to enhance melt flow in the mold, e.g., about380-385° C. for polyetherimide.

Satisfactory polymer-based stampers for use according to theservo-patterning process of the invention were obtained with severalamorphous thermoplastics, notably polycarbonates (PCs) andpolyetherimides (PEIs). PEI-based stampers were determined to besuperior to those based upon PC in view of their better chemicalresistance against the alcohols present in the as-deposited film orlayer of sol-gel and their better mechanical performance. However,PEI-type polymeric materials are more difficult to mold than PC-typepolymeric materials because of their high T_(g) and poor melt flowcharacteristics. PEI-based stampers provided clean release from thesol-gel after servo pattern stamping, enabling formation ofservo-patterned sol-gel disks operable at flying heights of about 0.5 μinch.

According to a second approach developed by the inventors, the surfacecharacteristics of a metal-based (e.g., Ni) stamper were modified tofacilitate a clean release from the sol-gel film or layer. The surfaceof a Ni-based stamper was modified by sputtering an about 500 to about1,000 Å thick layer of a material, such as, for example, platinum (Pt),carbon (C), or a polymeric material, which materials are characterizedby having a low surface energy and hydrophobic surface characteristics.In particular, Pt has been found to provide excellent results whencoated on the patterned surface of a Ni-based stamper, because it isdurable (thus allowing the stamper to be re-used a number of times),very inert, and its hydrophobic characteristics are enhanced by exposureto the ambient. Delamination of the Pt film from the Ni stamper surfacedue to contamination of the surface by organics can be effectivelyprevented by subjecting the Ni surface to cleaning in an oxygen (O₂)plasma or by reactive ion etching prior to sputter deposition of the Ptfilm. Further, according to a particularly advantageous method, thesputtering step can be incorporated into the stamper fabrication processas to eliminate any problems with adhesion. According to this method,the Pt layer is sputtered onto the patterned surface of a Ni-basedmother stamper and a Ni-based child stamper then formed over the Ptlayer on the mother stamper, as by electroforming. In this way, thechild stamper is formed on the Pt layer, and after the child stamper isseparated from the mother stamper, a Ni-based stamper with a Pt layer onthe surface thereof is obtained.

Thus, the present invention advantageously provides, as by processingtechniques and methodologies, including embossing of sol-gel layers,which can be practiced at low cost to yield improved, servo-patternedsubstrates comprised of high hardness, high modulus materials suitablefor the manufacture of high areal recording density magnetic recordingmedia, magnetic recording media including such improved, servo-patternedsubstrates, and improved stampers for performing the embossing.

In the previous description, numerous specific details are set forth,such as specific materials, structures, reactants, processes, etc., inorder to provide a better understanding of the present invention.However, the present invention can be practiced without resorting to thedetails specifically set forth. In other instances well-known processingmaterials and techniques have not been described in detail in order notto unnecessarily obscure the present invention.

Only the preferred embodiments of the present invention and but a fewexamples of its versatility are shown and described in the presentdisclosure. It is to be understood that the present invention is capableof use in various other combinations and environments and is susceptibleof changes and/or modifications within the scope of the inventiveconcept as expressed herein.

What is claimed is:
 1. A method of manufacturing a magnetic recordingmedium, comprising the sequential steps of: (a) providing a non-magneticsubstrate for a magnetic recording medium, said substrate including atleast one major surface; (b) forming a layer of a sol-gel on said atleast one major surface of said substrate; (c) forming a servo patternin an exposed surface of said layer of said sol-gel; and (d) convertingsaid layer of said sol-gel to a glass or glass-like layer whilepreserving said servo pattern in said exposed surface of said glass orglass-like layer.
 2. The method according to claim 1, wherein: step (a)comprises providing a disk-shaped, high modulus substrate having a pairof major surfaces and comprised of a glass, ceramic, or glass-ceramicmaterial.
 3. The method according to claim 1, wherein: step (b)comprises forming said layer of said sol-gel by spin coating a solutionof said sol-gel on said at least one major surface of said substrate. 4.The method according to claim 1, wherein: step (c) comprises embossingsaid servo pattern in said exposed surface of said layer of said sol-gelby applying thereto a surface of a stamper, said surface of said stamperincluding a negative image pattern of said servo pattern.
 5. The methodaccording to claim 4, wherein: step (b) comprises forming a layer of ahydrophilic sol-gel on said at least one major surface of saidsubstrate; and step (c) comprises embossing utilizing a stamper whereinat least said patterned surface thereof is formed of a hydrophobicmaterial.
 6. The method according to claim 5, wherein: step (c)comprises utilizing a stamper wherein at least said patterned surfacethereof is formed of a hydrophobic polymeric material.
 7. The methodaccording to claim 6, wherein: step (c) comprises utilizing a stamperwherein said hydrophobic polymeric material is an amorphousthermoplastic material.
 8. The method according to claim 5, wherein:step (c) comprises utilizing a stamper having a main body comprised of afirst metal and said patterned surface thereof is formed of a secondmetal, carbon, or a hydrophobic polymer.
 9. The method according toclaim 8, wherein: step (c) comprises utilizing a stamper wherein saidmain body is comprised of nickel and said patterned surface thereof isformed of platinum, carbon, or a sputtered hydrophobic polymer.
 10. Themethod according to claim 1, wherein: step (d) comprises sintering saidlayer of sol-gel at an elevated temperature.
 11. The method according toclaim 10, wherein: step (b) comprises forming a layer of a sol-gelcomprising a porous layer of SiO₂ containing water and at least onesolvent in the pores thereof; and step (d) comprises converting saidlayer of sol-gel to said glass or glass-like layer by driving out saidwater and said at least one solvent from said pores by sintering saidlayer of sol-gel at a temperature of from about 300 to above about 1000°C.
 12. The method according to claim 1, further comprising the step of:(e) forming a stack of thin film layers over said exposed surface ofsaid glass or glass-like layer, said stack of layers including at leastone ferromagnetic layer.